From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BA010C83000 for ; Tue, 28 Apr 2020 11:22:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9AD7A206D9 for ; Tue, 28 Apr 2020 11:22:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726522AbgD1LWD (ORCPT ); Tue, 28 Apr 2020 07:22:03 -0400 Received: from foss.arm.com ([217.140.110.172]:49720 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726458AbgD1LWD (ORCPT ); Tue, 28 Apr 2020 07:22:03 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 69C3730E; Tue, 28 Apr 2020 04:22:02 -0700 (PDT) Received: from C02TD0UTHF1T.local (unknown [10.57.1.132]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6B3713F73D; Tue, 28 Apr 2020 04:22:00 -0700 (PDT) Date: Tue, 28 Apr 2020 12:21:57 +0100 From: Mark Rutland To: Gavin Shan Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, steve.capper@arm.com, catalin.marinas@arm.com, broonie@kernel.org, will@kernel.org, shan.gavin@gmail.com Subject: Re: [PATCH v2] arm64/kernel: Fix range on invalidating dcache for boot page tables Message-ID: <20200428112157.GB15519@C02TD0UTHF1T.local> References: <20200427235700.112220-1-gshan@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200427235700.112220-1-gshan@redhat.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 28, 2020 at 09:57:00AM +1000, Gavin Shan wrote: > Prior to commit 8eb7e28d4c642c31 ("arm64/mm: move runtime pgds to > rodata"), idmap_pgd_dir, tramp_pg_dir, reserved_ttbr0, swapper_pg_dir, > and init_pg_dir were contiguous at the end of the kernel image. The > maintenance at the end of __create_page_tables assumed these were > contiguous, and affected everything from the start of idmap_pg_dir > to the end of init_pg_dir. > > That commit moved all but init_pg_dir into the .rodata section, with > other data placed between idmap_pg_dir and init_pg_dir, but did not > update the maintenance. Hence the maintenance is performed on much > more data than necessary (but as the bootloader previously made this > clean to the PoC there is no functional problem). > > As we only alter idmap_pg_dir, and init_pg_dir, we only need to perform > maintenance for these. As the other dirs are in .rodata, the bootloader > will have initialised them as expected and cleaned them to the PoC. The > kernel will initialize them as necessary after enabling the MMU. > > This patch reworks the maintenance to only cover the idmap_pg_dir and > init_pg_dir to avoid this unnecessary work. > > Signed-off-by: Gavin Shan Reviewed-by: Mark Rutland Mark. > --- > v2: Include the suggested commit log (Mark Rutland) > Improved comments and code (Mark Rutland) > --- > arch/arm64/include/asm/pgtable.h | 1 + > arch/arm64/kernel/head.S | 12 +++++++++--- > arch/arm64/kernel/vmlinux.lds.S | 1 + > 3 files changed, 11 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h > index 8c20e2bd6287..5caff09c6a3a 100644 > --- a/arch/arm64/include/asm/pgtable.h > +++ b/arch/arm64/include/asm/pgtable.h > @@ -457,6 +457,7 @@ extern pgd_t init_pg_dir[PTRS_PER_PGD]; > extern pgd_t init_pg_end[]; > extern pgd_t swapper_pg_dir[PTRS_PER_PGD]; > extern pgd_t idmap_pg_dir[PTRS_PER_PGD]; > +extern pgd_t idmap_pg_end[]; > extern pgd_t tramp_pg_dir[PTRS_PER_PGD]; > > extern void set_swapper_pgd(pgd_t *pgdp, pgd_t pgd); > diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S > index 57a91032b4c2..32f5ecbec0ea 100644 > --- a/arch/arm64/kernel/head.S > +++ b/arch/arm64/kernel/head.S > @@ -394,13 +394,19 @@ SYM_FUNC_START_LOCAL(__create_page_tables) > > /* > * Since the page tables have been populated with non-cacheable > - * accesses (MMU disabled), invalidate the idmap and swapper page > - * tables again to remove any speculatively loaded cache lines. > + * accesses (MMU disabled), invalidate those tables again to > + * remove any speculatively loaded cache lines. > */ > + dmb sy > + > adrp x0, idmap_pg_dir > + adrp x1, idmap_pg_end > + sub x1, x1, x0 > + bl __inval_dcache_area > + > + adrp x0, init_pg_dir > adrp x1, init_pg_end > sub x1, x1, x0 > - dmb sy > bl __inval_dcache_area > > ret x28 > diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S > index 497f9675071d..94402aaf5f5c 100644 > --- a/arch/arm64/kernel/vmlinux.lds.S > +++ b/arch/arm64/kernel/vmlinux.lds.S > @@ -139,6 +139,7 @@ SECTIONS > > idmap_pg_dir = .; > . += IDMAP_DIR_SIZE; > + idmap_pg_end = .; > > #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 > tramp_pg_dir = .; > -- > 2.23.0 >